Universal brake shoe grinder guide



Dec. 2, 1957,I L. c. Risi-|51. .2,102,915

' UNIVERSAL BRAKE SHOE GRINDER GUIDE Filed March 28, 1935 ZSheets-Shgae'fI l.

i @www Dec. 2l, 1937. L. c. RISHEL UNIVERSAL BRAKE SHOE GRINDER GUIDE Filed March 28, 1935 2 Sheets-Sheet 2 Inweb/02* L. 6. A.Y/lse/ by www Patented Dec. 21, 1937 UNITED STATES PATENT OFFICE UNIVERSAL BRAKE SHOE GRINDER GUIDE `Luther C. Rishel, Los Angeles, Calif.

Application March 28, 1935, Serial No. 13,462

21 Claims. (Cl. 51--96) My invention relates to a brake shoe grinder on a top plate on the brake shoe guide, the web guide designed to produce a true cylindrical occupies a horizontal position and is engaged by a ground face on the brake lining attached to the clamping screw. Thus the brake shoe is held brake shoe. rigidly on the guide, that is on the top plate of In certain types of brake lining grinders it is the guide by means of the clamping screw en- 5 necessary to have a set of guides, these having gaging the web and adjustable pins or the like an arcuate flange, each corresponding to brake contact the inner side of the iiange of the shoe. drums of different diameters. With this type it Another object and feature of my invention is is necessary to change the arcuate guide when in the adjustment of the contact pins, these belO brake shoes are to be ground to t different sizes ing preferably two in number and each mounted of brake drums. In another type, a plurality of in a slidable plate, each plate sliding in a radial removable pins may be replaced in different sockdirection on the structure forming the guide. The ets to obtain the proper curvature for grinding center of the radius for these sliding plates is the brake lining, the lining being pressed against fixed and is preferably the mean or average ral5 the pins and then rotated in an are while being dius of a series of different radii for which the 15 brought into contact with a grinding wheel. particular machine is designed to grind brake An object and feature of my invention is to emlinings. ploy a grinder guide which rotates on the axial Another object and feature of my invention is center defining the center of a brake drum, the preferably constructing the top plate of the movbrake shoe being suitably clamped so that the able guide with an edge formed on a curvature, 20

finished surface of the lining will conform to the radius of which is equal to-that of the smalla true cylinder of a brake drum of a deiinite est brake drum for which the machine is de- Vdiameter. Afurther feature is aconstruction by signed to grind brake shoes. This guide may which a center stud on which the guide maybe then be adjusted as to the rotary grinding wheel turned is adjustable to give a Series of variable to give the desired clearance for grinding a brake 2 5 radii, thus accommodating the grinder guide and shoe with its lining supported on the top plate the location of the shoe to brake drums of differ- 0f the guide. The Sliding plates haVng the adent standard diameters. justable contact pins are each provided with a A further feature of my invention is the propoint on their outer edge, which point may be advision of a fixed supporting structure attached justed to extend beyond the peripheral edge of 30 to a grinding machine, this being in a certain the top plate. These guide plates are set an equal relation to the grinding Wheel. On this xed distance on opposite sides of the central radial structure or support is mounted the adjustable line through the top plate and hence define with guide. The pivot stud may te adjusted radially the central point on the periphery 0f the t0n y.- on the fixed structure and the guide then plate, three points in the circle of any radius on clamped as to radial motion in relation'to the which it is desired to grind brake linings. The

stud, the stud however, permitting a rotation COntaCt DinS are adjustable by a micrometer adon the axis of the stud so that the guide may be justment to gauge the known thickness 0f the shifted to one side of the grinding wheel for brake shoe flange and the desired thickness of 40 attaching and clamping the brake shoe with the the finished brake shoe lining. 40 lining in position on the guide. My invention is illustrated in connection with A further feature of my invention relates to a the accompanying dra-Wings, in Which, clamp and a backing support for the brake shoe Fig. 1 is a plan taken in the direction of the by which the brake shoe with its lining may be arrow l of Fig. 2.

firmly secured to the guide structure, this clamp Fig. 2 is a vertical section on the line 2--2 of 45 having contact pins to contact the inner side Fig. 1, in the direction of the arrows. of the flange of a brake shoe and thus make cor- Fig. 3 is a vertical section on the line 3-3 of rect adjustment for the thickness of the flange Fig. 2 in the direction of the arrows, this being of the shoe and the thickness of the brake lintransverse to the section of Fig. 2.

.to ing. The shoes are usually made T-shaped in Fig. 4 is a horizontal section on the line 4 4 50 cross section with a flange formed on the cylinof Fig. 3 in the direction of the arrows. drical brake drum on which the shoe operates Fig. 5 is a detail vertical section on the line and each shoe is usually provided with a central 5 5 of Fig. 4 in the direction of the arrows. web. The web extends inward radially and hence In using my invention 'I may apply same to a when the lower edge ofthe brake shoe flange rests Aknown type of brake lining grinder. Such a V type has a central pedestal II with a head structure I2 extending above which is a rotating grinding wheel I3, this rotating on a vertical axis and having an abrasive on its periphery. In this type of machine there is a lateral extension I4 of the head on which is mounted a drilling device I5 for removing old rivets or the like from bra-ke shoes. When not in use this is provided with a coverrcap I6. This device does not enter into my invention but my guide is constructed to form a clearance with this.

In my invention I use a large flat base plate 26, with a perforation which has Van undersurface 2I resting on the iiat top 22 of the head I2 and the extension I4. This plate has an upper surface 23 and is provided with a convex edge 24 which is located to have a working clearance with the periphery of the grinding wheel I3. A pair of lateral ears 25 and 25 are located on opposite sides of the center line 2. One of these has a boss 28 having a perforation 29 through which extends a centering pin 36.

In the type of machine to which my invention may be attached, provision is made for a pin similar to the pin 36, therefore I adopt the setting of the plate 2!) to this machine. However, if there is no provision for such a pin, a hole may be drilled in the top of a brake shoe grinder to accommodate such a pin. 'Ihe ear 26 is held in place by means of a set screw 3I having a head 32 which screws upwardly through the extensionV I4 of the head I2. The upper end 33 oithis screw is threaded into a recess in the underside of the vplate 20. From the ears 25 andv26 there are two opposite laterally curved portions 34 having convex corners 35 joining into a straight section 36. These are connected by a vertical hub structure 3l', this hub structure 'giving a clear- Van around the drilling device I5.

Attached to the top of the hub there is a substantial arm 38. This arm has a central slot 39 through which extends an adjusting screw 46. This screw extends through a perforation GI at one end of the arm and has a bearingin a socket 42 at the inner end. A knurled finger grip head 43 is at the outer end of the arm. The screw is held in place by means of a collar 44 or the like, held in place by a pin 45 or similar structure. Thus the base plate with the arm 38 form a rigid structure which is attached as above described to Y the head I2 and the lateral extension I4 of the grinding machine.

The main guide structure for the brake shoe designated by the assembly numeral 50, employs a top plate 5I. This has a convex vertical curved edge 52, the plate having a flat undersurface 53 and also a flat top surface 54. A radius of the curve 52 is that of the smallest sized 'brake drum for which linings are to be ground with my machine and the setup. The convex curved edge terminates at two vertical edges 55 in alignment,

these being connected by a vertical concave edge 56, which in all conditions of operation is spaced from the hubl of the base plate.

Extending vertically from the top plate 5i and adjacent the center of the concave edge 56 there is 'an arcuate vertical short post 51, this beingV shown in horizontal section in Fig. 4 and in vertical section in Fig. 2; Formed integral with the post5'I there is a substantial arm 58. This arm has a fiat lower and upper surface and one edge 59- is preferably in alignment with the edge 6l) of the xed arm 38 of Vthe base. The other edge 6I of the arm 58 has a bevelled slope considered transversely (note Fig. 3) and forms a continuation surface with the edge 62 of the xed arm 38. The surface 6I is provided with scale gradulations 53and the surface 62 with scalergraducurvature of which the brake linings are to be ground.V

In the center portion of the arm 58 there are a series of V-shaped teeth 66 and also extending longitudinally of the arm there is a slot E?. This slot registers with the slot 39 of the fixed arm 33. In order to retain these arms in alignment, a retaining pin 68 which is removable, extends through perforations 69 in both the arms 58 and 38'.

The adjustable center pivot Vstud designated by the assembly numeral 10 consists of a central stud member 1| (note particularly Fig. 3), which passes vertically through the slot 3S in the xed arm 36, which arm as above mentioned is secured to the vertical hub 31. The adjusting screw 26 is threaded through a perforation 'l2 in thestud member ll. A sleeve 'I3 is fitted onV the stud member Vand the sleeve and stud member pass througha clamping plate 'I4 which plate has teeth on its undersurface to engage and register with the teeth 65 on the upper surface of the arm 58. This locking plate is preferably rectangular and bridges the slot'I of the arm 5'8. The clamping plate is provided with a nger tab 'I5 to facilitate lifting of such plate for purpose hereinunder detailed. A spring washer 76 surrounds the sleeve 73 in the stud member 1I. the stud is threaded at 'I'I and on this is threaded a clamping nut 18. VThis nut has a large head 'E9 Ypreferably knurled to orrn a hand grip and has an annular lower surface 86 to bear on the spring washer 'I6 and thus to transmit a clamping pressure on the clamping plate le. Y

In order to indicate the correct adjustment of this movable pivot stud, a Vlower pointer arm SI is rixedly secured to the lower end of the stud 'il and extends Ytransversely to one side under the arm 33. This has'an upturned pointer finger B2 which registers with the scale 64 on the side edge 62 of the lower arm 38. An upper pointer nger 83 is attached to one side of the clamping plate 'Iii and extends partly over the edge 6I of lows: A substantial clamping arm 35 is secured l to the upper end of the short Vprost 5l', Vbeing preferably integral therewith and is in alignment with the arm 58.V At the outer end ofthe arm 85 there is aclamping screw 86 threaded through the arm. The lower end of this clamping screw is adapted to engage the web 8l of the brake shoe 88 which shoe has an arcuate iiange 89 extending on opposite sides of the Web and to which flange is secured the brake lining Si! which lining is to be` ground to the correct cylindrical curve of a brake drum with which it operates. The lower edge 9| of the flange and of the brake lining rests on the upper surface of the movable top plate 5I and if this brake shoe is of a size to operate with the smallest size brake drum for which the present machine is designed to The upper end of grind, the arcuate edge 52Y of the movable top Y diameter, the end portions of the shoe and its lining will extend beyond the edge 52 as shown in Fig. l. A handle 92 is provided on the combined arms S and 85 so that the top plate 5| may be rotated in an arc with the pivot stud as a center as hereinunder detailed.

In order to accurately center and hold a brake shoe clamped on the top plate 5|, I employ an inner contact assembly designated $5 (note particularly Figs. 3 and 4). This employs two slidable plates 96 which slide in flat grooves or recesses 91 in the top plate 5|. 'I'hese grooves are preferably dove-tailed as indicated at 98 of Fig. 5. Each plate 95 thus has two parallel side edges 99 and the outer edge |50 has two slopes meeting at a vertical edge IEII. The center line |02 through this vertical edge and the axial center of each sliding plate 95 preferably forms a radius from a certain center |53. This point is Such that it defines the center oi the mean radii for which the machine is designed to grind brake linings. For instance, in the scale 63 the numerals 55 indicate that the particular setup is designed to grind brake shoes to fit brake drums to 16" in diameter. Thus the center ||l3 would be at a position ior a brake drum 13" in diameter, thus 6% in radius.

The means for moving each of the sliding plates 95, comprises an adjusting screw its which extends through a i'lxed lug |55 on the top plate 5|. This screw has a knurled head |95 and is prevented from endwise movement by collars |01. The s crew then is threaded through a boss |08 in the plate 95. Thus by rotating the screws |54 the two plates 55 may be adjusted longitudinally.

In order to obtain the correct adjustment ci each brake shoe I employ two contact pins lill. Each of these pins is provided with screw threads operating through a threaded boss H2 secured to each of the plates 96. The axis of the pin is as near the radius line |52 as it may be conveniently located.V One end of the pin has an operating knurled head ||3 and the opposite end has a conical pointed end lili. On the threaded portion there is a knurleol lock nut i5. A Vernier H5 has graduations ||l on each pin ||U adjacent its head l, which graduations may register with a xed line i i8 on the boss l i2.

The manner of adjusting'the plates 96 is as k follows: On the top plate 5| there are a series of Y operated by the knurled head 43,

graduations marked oli" with lead lines |2| to numerals |22, these numerals corresponding to the diameters of the drums indicated on the scales 83 and Ed by the numeral 65. A registry line |23 is formed on each slide plate 96.

The manner of operating my invention is as follows: When the pivot stud designated by the assembly numeral 'lil is in place, extending through both of the arms 38 and 58 and the pin 68 is in the perforations or sockets |59, these two arms are held in alignment. The pivot stud is then adjusted lengthwise of the slots 39 and 6l by means of the adjusting screw 55' which is However, before the stud can be moved it is necessary to loosen the nut 19 threaded on the upper end of the stud member 1| and also to lift the clamping plate M by means of the linger grip tabs l5 to form a clear disengagement of the teeth 55 on the arm 55 and the teeth on the underside of the clamping plate I4.

Presuming the brake drum is of a true diameter as originally constructed on a wheel: this is nusually a certain definite number of inches in diameter and the pivot stud is so adjusted untilv the pointer ngers 82 and 83 connected to the stud and the clamping plate respectively, register with the same diameter number on the scales 63 and 54. In the illustrations of Fig. 1, this is shown as registering with the diameter of 13, thus giving a radius of 61/2". However, if the brake drum has been turned down on the inside, a measurement should be made of the correct diameter and the pivot stud set accordingly. This is done with the two arms 33 and 58 locked together.

The sliding plates 955 are then adjusted by means of the adjusting screws |54 until the line mark |23 aligns with the scale |26 corresponding to the similar diameter marks on the scales 53 and 6d. This brings the vertical edge Il on each plate S5 and the center point |2l| on the top plate 5|, this being on the radius line 2l, the same distance or radius from the center of the pivot stud. The thickness of the flange 59 and of the finished brake lining is then determined. Each of the adjusting pins is first threaded outwardly until its point is approximately at the edge ||l| of the plate 95 on which it is mounted. Each screw is then retracted the correct distance indicated by the micrometer adjustment H5 so that the point of each screw is spaced from the edge or point |55, the thickness of the iiange 89 and the finished lining. Each contact pin is then locked in position by the lock nut H5. The slidahle plates 95 should irst be locked in their adjusted position which may be done by means of a wedging disk held in place by a screw |25 (note Figs. 4 and 5) each wedging disk h aving a surface to engage one of the dove tailedside edges of the adjacent slide plate S5.

When this adjustment has been made the pin 58 may be removed and by means of the handle 92 the whole of the top plate 5| with the arms 58 and 85 may be swung in an arc using the pivot stud 'lil as the center. This shifts the concave edge portion 52 of the plate 5| entirely to one side of the grinding wheel I3. The brake shoe with its lining is then adjusted on the upper surface 55 of the top plate 5|, the contact pins contacting the inside of the ilange 89 of the shoe and the clamping screw 85 being jammed downwardly on the web 8l. The shoe should be so located that it extends approximately evenly on opposite sides of the radial line through the arms 5B and 85. The grinding wheel is then started in rotation and the assembly having the top plate 5| with the brake shoe clamped thereto is slowly swung in an arcy by means of the handle S2 and the surface ofthe brake lining .is ground ofi" by the grinding wheel I3 starting at one end of the shoe and continuing to the other end. This gives a complete grinding of the brake lining down to a surface indicated by the position of the points |U| on the slide plates 95 and the point |2fl on the tcp plate 5|, these having a slight clearance from the grinding wheel. Thus the brake lining may be ground down complete, tak-ing off the high spots down to the lowest spot or portion of the lining. When the brake lining is. thus after grinding, positioned at one side oi the grinding wheel, the shoe may be removed by merely unthreading the clamping screw B5.

The adjustments made by the sliding plates 95 and the contact pins mi are not absolutely correct as to measurement for all diameters of drums, hence, it is necessary to lock the scale |213 on the xed plate 5| empirically, that is by making the actual measurements for` certain sized drums.

The micrometer adjustmentv I I6 also gives a close approximation to the thickness of the ange of the brake shoe and the brake lining on a radial line. This may also be made to conform to the slight offset that the axes of the contact pins I I I have with the various radial lines from the pivot stud.

Various changes may be made in the details of construction without departing from the spirit or scope of the invention as dened by the appended claims.

I claim:

l. In a grinding machine for brake shoes, having a pedestal with a rotatable grinding wheel, a base plate rigidly secured to the pedestal and having a longitudinal slot with a screw therein, the screw being on a radial line from the center of the grinding wheel, a rigid top plate having a longitudinal slot, means to temporarily secure the base and top plates with their slots in alignment, a pivot stud threaded on the screw and extending through the slot of the top plate, a clamping device for clamping the top plate to the stud, said device permitting rotation of the top plate on the stud as an axis after removal of the temporary securing means, and means for mounting a brake shoe with its lining on the top plate whereby the shoe may be ground on a radius defined by the distance between the axis of the stud and the eriphery of the grinding wheel, the means for mounting the brake shoe comprising a pair oi slidable plates mounted on the top plate and each having a sliding motion from a fixed center, the said center being in oneposition relative to the screw, a contact pin adjustably mounted on each sliding plate to engage the inner side of aY flange of a brake shoe, a clamping screw secured to the top plate to engage the web of a brake shoe, the said sliding plates and a portion oi' the top plate forming a three point contact for the edgeof the flange of the brake shoe and the lining attached thereto. Y

2. In a grinding machine for brake shoes, having a pedestal, a grinding wheel mounted thereon, a fixed structure having an arm with a slot therein, a screw extending through the slot and having a stud threaded thereon, the screw being in radial alignment with the 'grinding wheel, a top plate having a second arm with a slot, an adjusting means engaging the said studV and the second arm, means to temporarily align said arms to bring the second arm into radial alignment with the grinding wheel, the said top plateV having a convex curvature on its edge or" a radius equal to the smallest radius of brake shoe to be ground, and means on the top plate to support a brake shoe on its edge, and a clamping means i'or the brake shoe, the supporting means for the brake shoe on topV plate comprising slide plates mounted on the top plate, there being at least two slide plates, one on each side of the radial line from the screw to the grinding wheel, and each Yslide plate having a contact pin to engage the back of' a brake shoe, the two slide plates and the portion of the top plate midway therebetween forming a three point support of an edge of the brake shoe.

3. In a grinding machine for brake shoes, having a pedestal, a grinding wheel mounted thereon, a xed structure having an arm with a slot therea screw extending throughthe slot and having a stud threaded thereon, the screw being in radial alignment with the grinding wheel, a top plate having a second arm witha slot, an adjusting means'engaging the said stud and the second arm,

means to temporarily align said arms to bring the second arm into radial alignment with the grinding wheel, the said top plate having a convex curvature on its edge of a radius equal to the smallest radius of brake shoe to be ground, and means on the top plate to support a brake shoe on its edge, and a clamping means Vfor the brake shoe, each '0f the arms having complementary scales, and a pointer means to indicate the, radius of grinding a brake lining, the said scales being'in alignment when the two arms are in radial alignment with the grinding Wheel, the top plate having slide plates to support the brake shoe and complementary scales on the top plate and slide plates to indicate the radius of grinding of a brake lining.

4. In a grinding machine forV brake shoes, a fixed structure having a 'rotating grinding wheel, a rotatable supporting structure for brake shoes adjustably mounted on the xed structure on a radius of the grinding wheel, the rotatable structure having at least two slide plates mounted thereon, each slidable on a radius approximately from thercenter of rotation of the rotatable structure, contact pins adjustably mounted on the slide plates, and a clamp on the rotating structure to clamp aV brake shoe. Y

5. In a grinding machine as claimed in claim 4, the rotatable structure having a convex curve on a portion of its periphery, such curve having a center portion to substantially contact with the grinding wheel, the sliding plates being on opposite sides of the center line, the convex curve being of a radius of the smallest shoe to be ground, the center portion of the rotatable strucprovide for a rotation of the top plate on the stud, means for mounting a brake shoe with a lining on the top plate, whereby the supporting structure with its top plate may be turned in an arc on the pivot stud to engage the grinding wheel and grind the shoe on anarc having a radius dened by the axis of the stud and the periphery of the grinding wheel, the means for mounting the brake shoe on the top plate comprising a pair of slidable plates mounted on the top plate, each plate forming with a portion of the top plate a three point contact with an edge of a brake shoe and the lining thereon, and a clamp to secure the brake shoe to the top plate.

7. In a grinding machine having a pedestal with a grinding wheel operating on a vertical axis, a drilling device spaced therefrom, the pedestal having aV centering pin offset from the grinding wheel combined with a base plate having a centering perforation engaging the saidV pin, a set screw attaching another portion of the base plate to the pedestal, the baseplate having van arcuate hub extending upwardly therefrom to partly surround the drilling devic'ea horizontal arm extending from the hub and being radial to the grinding wheel, a top plate having a flat portion resting on the base plate and having a post extendingrupwardly spaced from the said hub, a second arm connected to the post, an adjustable pivotal connection between the said arms, means'for clamping a brake shoe to the portion of the top plate resting on the base plate and means for swinging the top plate with the brake shoe in an arc on the pivotal connection between the said arms for grinding the shoe by the grinding wheel.

8. In a grinding machine as claimed in claim '7, the two arms when in alignment having a beveled edge on substantially the same slope, the beveled edge of each arm having scale graduations, the pivotal connection of the arms being by a pivot stud, a pointer finger connected to the lower end of said stud and having a pointer adjacent the scale on the lower arm, an upper pointer nger mounted on the stud and having a pointer adjacent the scale on the upper arm.

9. In a grinding machine as claimed in claim '7, the portion of the top plate which rides on the base plate having a pair of slidably adjustable plates and such portion of the top plate having a convex curve approximating that of the smallest brake shoe to be ground whereby the edge of the brake shoe is supported on the slide plates and a portion of the top plate between the slide plates and a contact pin adjustably mounted on each slide plate to engage the back of a brake shoe.

10. In a grinding machine for brake shoes having a base plate with a perforation adapted to engage a centering pin on a pedestal, a set screw for attaching another portion of the top plate to a pedestal, the base plate having a flat portion surface adapted to rest on a pedestal, an arcuate hub extending upwardly from the flat portion and adapted to accommodate a drilling device mounted on a pedestal, a iirst arm extending from the said hub in a direction opposite the center line of the base plate, a top plate having a flat portion to slide on the ilat portion of the base plate, a post extending upwardly therefrom and spaced from the hub, a second arm connected to the post and adapted to align with the nrst arm of the base plate, means to clamp a brake shoe to the top plate, a pivot stud connecting said arms, means to adjust said stud longitudinally of the arms whereby the top plate with the brake shoe may swing in an arc on the said stud as a center and adapted for grinding a brake lining by a grinding wheel mounted on a pedestal.

1l. In a grinding machine as claimed in claim 10, the means to adjust the stud comprising a screw on the arm of the base plate, the stud being threaded on the screw, the second arm having a slot, the upper surface of the second arm having teeth, a clamping plate on the stud engaging said teeth, a nut on the stud engaging the clamping plate, the adjacent marginal edges of the said arms 'having scales, a first pointer arm connected to the lower part of the stud and having a pointer operating over the scale on the first arm connected to the base plate, the clamping plate having a second pointer arm with a pointer operating over the scale of the second arm connected to the top plate.

12. In a grinding machine as claimed in claim 10, the portion of the top plate on which the brake shoe is mounted having a convex edge of a curvature approximating that of the smallest brake shoe to be ground, a pair of slide plates mounted on said portion of the top plate and adjustable thereon, the direction of sliding being approximately radial to the average position of the pivot stud, each sliding plate having a contact pin adjustable thereon to engage the back of a brake shoe in approximately the radial line through the center of the' slide plate on which it is mounted, each slide plate having an end portion positioned contiguous to the convex edge of the top plate whereby the edge ofv a brake shoe may be supported on the two slide plates and a portion of the top plate between the slide plates.

13. In a grinding machine for brake shoes having a grinding wheel, a relatively xed structure having a first arm, a pivot stud adjustably mounted thereon, a top plate having a second arm adjustable on the stud, each of the arms having complementary scales to be brought into registry, a pointer connected to the stud and operative on the scale on the rst arm, a second pointer connected to the stud and operative on the scale of the second arm, the said scales being in alignment when the two arms are in radial alignment with a grinding wheel, the top plate having means to'clamp a brake shoe.

14. In a grinding machine for brake shoes having a grinding wheel, a relatively xed structure having a rst arm, a top plate having a second arm, a pivot stud interconnecting said arms and defining a radial distance between the stud and the grinding wheel, each of the arms having complementary scales and a pointer means to indicate the radius of grinding a brake lining, the said scales being in alignment when the two arms are in radial alignment with the grinding wheel, the top plate having slide plates to support the brake shoe, and complementary scales on the top plate and slide plates to indicate the radius of grinding of a brake lining.

15. In a grinding machine, a grinding wheel, a fixed structure having an adjustable pivot stud, a rigid top plate adjustable relative to said stud, a pair of slide plates adjustably mounted on the top plate and sliding approximately in a radial line relative to the pivot stud, the top plate having a convex edge on a curve from the pivot stud approximately the same as that of the smallest brake shoe to be ground, the said slide plates and the portion of the top plate midway therebetween and contiguous to the convex edge being adapted to form a three point support for an edge of a brake shoe having a lining projecting from such edge and a clamping means cooperative with the two slide plates and with the mid portion of the top plate between the slide plates for holding a brake shoe for grinding, the top plate being rotatable on the said stud for bringing a brake lining in contact with the grinding wheel.

16. In a grinding machine as claimed in claim 15, each slide plate being movable to project beyond the convex edge of the top plate to form part of the support for brake shoes of greater radius than the curvature of the convex edge of the top plate and a contact pin adjustably mounted on each slide plate to engage the back of a brake shoe.

17. In a grinding machine as claimed in claim 15, a first pair of scales having one part on the i'lxed structure and another part on the top plate, these being alignable when parallel to a line through the stud and the center of the grinding wheel to indicate the radial distance from the stud to the periphery of said wheel, and a pair of scales having complementary elements on the top plate and each slide plate to indicate the radius for grinding a brake shoe.

18. In a grinding machine having a grinding wheel, a xed base plate having an arm positioned in a radial line from the grinding wheel, a top plate having a at portion resting on the base plate and having a second arm, a stud adjustably mounted on the iirst arm, a clamp to clamp the second arm to the stud, the two arms when in alignment having a beveled edge of substantially the same slope, the beveled edge of each arm having scale graduations, the pivot stud forming a pivotal connection of the said arms, a pointer finger connected to the lower end of the stud and having a pointer adjacent the scale on the lower arm, an upper pointer finger mounted on the stud adjacent the clamp engaging the second arm and having a pointer adjacent the scale on the second arm.

19. In a grinding machine for brake shoes, a grinding wheel, a base plate having a first arm extending in substantially the center line through the base plate and the grinding wheel, a top plate having a fiat portion to slide on a flat portion of the base plate, a second arm connected to the top pla-te, a pivot stud connecting said arms and means to adjustthe stud'comprising a screw on the arm of the base plate, the stud being threaded on the screw, the second arm having a slot, the upper surface of the second arm having teeth, a clamping plate on the stud engaging said teeth, a nut on the stud engaging the clamping plate, the adjacent marginal edges of the said arms having scales, a rst pointer arm connected to the lower part of the stud and having a pointer operating over the scale on the first arm connected to the base plate, the clamping plate having a second pointer arm with a pointer operating over the scale of the second arm connected to the top plate.

20. In a grinding machine for brake shoes, a grinding wheel, a base plate, an adjustable centering and pivot stud mounted on the base plate, a top plate mounted on the base plate, an interengaging means between the top plate and the stud, the portion of the base plate and the top plate adjacent the stud having complementary scales which may be brought into'alignment to indicate the radius for grinding a brake shoe, the portion of the top plate which rides on the base plate having a pair of slidably adjustable plates and such portion of the top plate between the slide plates having a convex curved edge approximating that of the smallest brake shoe to be ground whereby the edge of the brake shoe is supported on the slide plates and a portion of the top plate between the slide plates, a contact pin adjustably mounted on each slide plate to engage the back of a brake shoe, complementary scales on the top plate and each slide plate to indicate the radius for grinding a brake shoe andV a clamping means on the top plate Vto engage a portionrof a brake shoe and hold such shoe in a clamped position for grinding relative to the slide plates and the portion of the top plate therebetween.

21. In a grinding machine for brake shoes, a grinding wheel, a xed base plate, an adjusting screw mounted thereon and extending in a radial line from the center of the grinding wheel, a'rigid top plate, a pivot stud longitudinally movable on the screw, a pivot connection between the top plate and the stud, th-e top plate having means for mounting a brake shoe comprising a pair of slidable plates mounted on the top plate and each having a sliding motion from a fixed center, the said center being in one position relative to the screw, a contact pin adjustably mounted on each sliding plate to engage the inner side of the flange of a brake shoe, a clamping screw secured to the top plate to engage the web of a brake shoe, the Said slidable plates and a portion of the top plate between said slidable plates forming a three point contact for the edge of the flange of a brake shoe to position the lining contiguous to the grinding wheel. Y

LUTHER C. RISHEL. 

